BackgroundAfrican animal trypanosomosis (AAT) is a major constraint to sustainable development of cattle farming in sub-Saharan Africa. The habitat of the tsetse fly vector is increasingly fragmented owing to demographic pressure and shifts in climate, which leads to heterogeneous risk of cyclical transmission both in space and time. In Burkina Faso and Ghana, the most important vectors are riverine species, namely Glossina palpalis gambiensis and G. tachinoides, which are more resilient to human-induced changes than the savannah and forest species. Although many authors studied the distribution of AAT risk both in space and time, spatio-temporal models allowing predictions of it are lacking.Methodology/Principal FindingsWe used datasets generated by various projects, including two baseline surveys conducted in Burkina Faso and Ghana within PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign) national initiatives. We computed the entomological inoculation rate (EIR) or tsetse challenge using a range of environmental data. The tsetse apparent density and their infection rate were separately estimated and subsequently combined to derive the EIR using a “one layer-one model” approach. The estimated EIR was then projected into suitable habitat. This risk index was finally validated against data on bovine trypanosomosis. It allowed a good prediction of the parasitological status (r2 = 67%), showed a positive correlation but less predictive power with serological status (r2 = 22%) aggregated at the village level but was not related to the illness status (r2 = 2%).Conclusions/SignificanceThe presented spatio-temporal model provides a fine-scale picture of the dynamics of AAT risk in sub-humid areas of West Africa. The estimated EIR was high in the proximity of rivers during the dry season and more widespread during the rainy season. The present analysis is a first step in a broader framework for an efficient risk management of climate-sensitive vector-borne diseases.

BackgroundTsetse flies are the sole vectors of human and animal trypanosomosis. In Burkina Faso, a project aiming to create zones free of tsetse flies and trypanosomosis was executed from June 2006 to December 2013. After the determination of tsetse distribution in the intervention area from December 2007 to November 2008, the control campaign was launched in November 2009 and ended in December 2013. The goal was to eliminate tsetse flies from 40,000 km2 of area, through an integrated control campaign including insecticide targets, traps and cattle, sequential aerial treatment (SAT) and the mass treatment of livestock using trypanocides. The campaign involved assistance of the beneficiary communities at all the steps of the control strategy with insecticide impregnated targets.MethodsThis study was carried out to assess the impact of the control project on tsetse apparent density per trap per day (ADT). To evaluate the effectiveness of tsetse control, 201 sites were selected based on the baseline survey results carried out from December 2007 to November 2008. These sites were monitored bi-monthly from January 2010 to November 2012. At the end-of-study in 2013 a generalized entomological survey was carried out in 401 infested sites found during the longitudinal survey done before the control. Barrier and tsetse persistence areas were treated by ground spraying and evaluated. Controls were also done before and after aerial spraying.ResultsIn the insecticide-impregnated target area, the control showed that ADT of tsetse flies declined from 10.73 (SD 13.27) to 0.43 (SD 2.51) fly/trap/day from the third month of campaign onwards (P < 0.0001) and remained low thereafter. At the end of the campaign in 2013, an 83% reduction of ADT was observed for Glossina palpalis gambiensis and a 92% reduction for G. tachinoides. Tsetse flies were captured only in 29% of the sites found infested in 2008.ConclusionsTsetse flies could be suppressed efficiently but their elimination from the targeted area may require the use integrated methods including the Sterile Insect Technique, which is programmed through the development of the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC Burkina) insectarium. The challenge will remain the sustainability of the achievement.Electronic supplementary materialThe online version of this article (10.1186/s13071-017-2609-3) contains supplementary material, which is available to authorized users.

In view of gathering baseline information about the prevalence of animal trypanosomosis, the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) funded a cross sectional survey in the Region of the Boucle du Mouhoun which constitutes the Northern limit of the tsetse distribution in Burkina. This cross sectional study was carried out in 53 villages located in the 6 provinces of the region. A total of 2002 cattle, 1466 small ruminants and 481 donkeys were sampled. This survey showed that about 25% of the cattle had been treated with trypanocidal drugs within 3 months before the survey compared to 3% and 0.42% for the small ruminants and donkeys respectively. Parasitological prevalence in cattle was low: 0.77% (95% C.I. 0.30-1.95%). No goats and three donkeys were found infected with trypanosomes. Infections were mainly due to Trypanosoma vivax (75.0%) with cases of T. congolense (25.0%). In cattle, the serological prevalence of trypanosomosis, for the entire Region of the Boucle du Mouhoun, was 34.2% (95%C.I. 26.1-43.4%). For sheep, goats and donkeys, the prevalence were of 20.9% (95%C.I. 12.2-33.5%), 8.5% (95%C.I. 5.7-12.5%) and 5.8% (95%C.I. 3.9-8.6%) respectively.The age and distance to the river were the two main risk factors associated with seropositivity.

Le système d’information géographique constitue une aide considérable lors de la définition d’un plan de lutte contre les glossines. Son application pratique pour la collecte de données entomologiques servant de base à la planification de la lutte et à son évaluation future a été faite dans l’ouest du Burkina Faso, de décembre 2007 à novembre 2008. Choisie pour englober les bassins versants des principaux fleuves ou rivières et les limites de distribution de Glossina palpalis gambiensis et G. tachinoides, la zone d’étude a été divisée en cellules de 10 km x 10 km. Dans chaque cellule, un maximum de 13 sites potentiels de piégeage ont été sélectionnés par l’utilisation d’imagerie satellite, puis repérés sur le terrain à l’aide du système mondial de positionnement (GPS). L’enquête entomologique a été réalisée avec des pièges biconiques Challier-Laveissière et les récoltes ont eu lieu 72 heures après leur installation. L’analyse des données a été conduite en utilisant des modèles aléa­toires mixtes binomiaux et de distribution de Poisson. La cartographie, réalisée avec le logiciel Arc Gis 9.3, a permis de déterminer la limite nord (12° 45’ N) des glos­sines dans la zone d’intervention. Les proportions de sites infestés étaient de 89,6 et 76,4 % respectivement au niveau des sections ascendante et descendante de la rivière Mouhoun (la première coule vers le nord-est depuis la source, la seconde vers le sud-est puis le sud après avoir conflué avec le Sourou), et de 16,7 et 10,3 % respectivement au niveau de leurs affluents. Entre les isohyètes 700–800 m et 800–900 m aucune différence significative n’a été observée dans les densités apparentes des glossines par piège, ni dans les sites infestés. Les deux espèces de glossines cap­turées étaient distribuées différemment selon les sections du Mouhoun : les cap­tures étaient composées de 79,5 % de G. p. gambiensis sur la section ascendante et de 96,0 % de G. tachinoides sur la section descendante. Les captures de vecteurs mécaniques ont été relativement faibles, leur distribution étant comparable à celle des glossines avec cependant quelques densités importantes sur les affluents.

Background African animal trypanosomosis (AAT), transmitted by tsetse flies, is arguably the main disease constraint to integrated crop-livestock agriculture in sub-Saharan Africa, and African heads of state and governments adopted a resolution to rid the continent of this scourge. In order to sustainably reduce or eliminate the burden of AAT, a progressive and evidence-based approach is needed, which must hinge on harmonized, spatially explicit information on the occurrence of AAT and its vectors. Methods A digital repository was assembled, containing tsetse and AAT data collected in Burkina Faso between 1990 and 2019. Data were collected either in the framework of control activities or for research purposes. Data were systematically verified, harmonized, georeferenced and integrated into a database (PostgreSQL). Entomological data on tsetse were mapped at the level of individual monitoring traps. When this was not possible, mapping was done at the level of site or location. Epidemiological data on AAT were mapped at the level of location or village. Results Entomological data showed the presence of four tsetse species in Burkina Faso. Glossina tachinoides, present from the eastern to the western part of the country, was the most widespread and abundant species (56.35% of the catches). Glossina palpalis gambiensis was the second most abundant species (35.56%), and it was mainly found in the west. Glossina morsitans submorsitans was found at lower densities (6.51%), with a patchy distribution in the southern parts of the country. A single cluster of G. medicorum was detected (less than 0.25%), located in the south-west. Unidentified tsetse flies accounted for 1.33%. For the AAT component, data for 54,948 animal blood samples were assembled from 218 geographic locations. The samples were tested with a variety of diagnostic methods. AAT was found in all surveyed departments, including the tsetse-free areas in the north. Trypanosoma vivax and T. congolense infections were the dominant ones, with a prevalence of 5.19 ± 18.97% and 6.11 ± 21.56%, respectively. Trypanosoma brucei infections were detected at a much lower rate (0.00 ± 0.10%). Conclusions The atlas provides a synoptic view of the available information on tsetse and AAT distribution in Burkina Faso. Data are very scanty for most of the tsetse-free areas in the northern part of the country. Despite this limitation, this study generated a robust tool for targeting future surveillance and control activities. The development of the atlas also strengthened the collaboration between the different institutions involved in tsetse and AAT research and control in Burkina Faso, which will be crucial for future updates and the sustainability of the initiative. Graphical Abstract

Tsetse flies are cyclical vectors of trypanosomes, the causative agents of sleeping sickness or Human African Trypanosomosis and nagana or African Animal Trypanosomosis in Sub-Saharan Africa. The Insectarium de Bobo-Dioulasso (IBD) was created and equipped in the frame of Pan African Tsetse and Trypanosomosis Eradication Campaign (PATTEC) with the main goal to provide sterile males for the different eradication programs in West Africa which is already the case with the ongoing eradication program in Senegal. The aim of this study was to identify the best feeding regime in mass-rearing colonies of Glossina palpalis gambiensis to optimize the yield of sterile males. We investigated the mortality and fecundity for various feeding regimes and day alternation (3×: Monday-Wednesday-Friday, 4×: Monday-Wednesday-Friday-Saturday, 4×: Monday-Wednesday-Thursday-Friday and 6×: all days except Sunday) on adult tsetse flies in routine rearing over 60 days after emergence. The day alternation in the 4 blood meals per week (feeding regimes 2 and 3) had no effect on tsetse fly mortality and fecundity. The best feeding regime was the regime of 4 blood meals per week which resulted in higher significant fecundity (PPIF = 2.5; P = 0.003) combined with lower mortality of females (P = 0.0003) than the 3 blood meals per week (PPIF = 2.0) and in similar fecundity (PPIF = 2.6; P = 0.70) and mortality (P = 0.51) than the 6 blood meals per week. This feeding regime was extended to the whole colonies, resulting in an improved yield of sterile males for the ongoing eradication program in Senegal and would be more cost-effective for the implementation of the next-coming sterile insect technique (SIT) programs in West Africa.

Background African animal trypanosomosis (AAT), transmitted by tsetse flies, is arguably the main disease constraint to integrated crop-livestock agriculture in sub-Saharan Africa, and African Heads of State and Government have adopted a resolution to rid the continent of this scourge. In order to sustainably reduce or eliminate the burden of AAT, a progressive and evidence-based approach is need, which must hinge on harmonized, spatially-explicit information on the occurrence of AAT and its vectors.MethodsA digital repository containing tsetse and AAT data collected in Burkina Faso between 1990 and 2019 was assembled. Data were collected either in the framework of control activities or for research purposes. Data were systematically verified, harmonized, georeferenced and integrated into a database (PostgreSQL). Entomological data on tsetse were mapped at the level of individual monitoring trap. When this was not possible, mapping done was at the level of site or location. Epidemiological data on AAT were mapped at the level of location/village.ResultsEntomological data showed that presence of four tsetse species in Burkina Faso. Glossina tachinoides was the most widespread and abundant species (56.35% of the catches), present from the eastern to the western part of the country. Glossina palpalis gambiensis was the second most abundant species (35.56%), and it was mainly found in the West. Glossina morsitans submorsitans was found at lower densities (6.11%), with a patchy distribution in the southern parts of the country. One only cluster of G. medicorum was detected (less than 0.1%), located in the Southwest. For the AAT component, data for 54,948 animal blood samples were assembled from 218 geographic locations. The samples were tested with a variety of diagnostic methods. AAT was found in all surveyed departments, including the tsetse-free areas in the North. Trypanosoma vivax and T. congolense infections were the dominant species 6.11±21.56% and 5.19±18.97% respectively), and to a lesser extend T. brucei infections (0.00±0.10%).Conclusions The atlas provides a synoptic view of the available information on tsetse and AAT distribution in Burkina Faso. Data are very scanty for most of the tsetse-free areas in the northern part of the country. Despite this limitation, this study generated a robust tool to aid the targeting of future surveillance and control activities. The development of the atlas also strengthened the collaboration between the different institutions involved in tsetse and AAT research and control in Burkina Faso, which will be crucial for future updates and the sustainability of the initiative.